1. Field of the Invention
Exemplary embodiments relate to a semiconductor integrated circuit, and more particularly, relate to a flip-flop circuit.
2. Description of the Related Art
Digital logic systems are classified into combinational circuits and sequential circuits. Combinational circuits are formed of logic gates, outputs of which are decided by current inputs. Combinational circuits perform an information processing operation which is logically characterized by the Boolean expressions.
Sequential circuits use storage elements called a flip-flop together with logic gates. Outputs of storage elements are a function of their inputs and states. States of storage elements are a function of previous inputs thereof. As a result, outputs of sequential circuits are based on current inputs and previous inputs, and operations of sequential circuits are decided by internal states and a time sequence of inputs.
Accordingly, high-speed flip-flops are required to design high-speed chips. Flip-flops with a conventional master-slave structure are not suitable for designing high-speed chips.